Oil is the basis of income in the country, it makes up 87% of exports and 75% of government income. It has placed Kuwait within the top 10 countries in the world for rent per-capita.
The continental climate and scarcity of natural water sources make development in the agricultural sector virtually unviable. This also means that water and most food products have to be imported.
If you are going to work in Kuwait, it is recommended that you make contact with the Kuwait embassy in Madrid, where they will advise you regarding customs, visas and permissions that you need to enter and live in the country.
If you need more information once you have arrived in Kuwait you can always contact the Spanish embassy in Kuwait.
Other interesting links regarding your move to Kuwait: